This invention relates to optical attenuators and, more particularly, to a device for attenuating a polarized light beam. In optical bar code scanners which are found in retail stores, the power of the scanning light beam outputted by the scanner must be tightly controlled to meet both governmental regulations and performance requirements. Typically, this is accomplished by using a high power laser and attenuating the laser light beam. This usually requires a selection of one of several, relatively expensive, coated glass attenuators. Another technique for accomplishing this is to vary the degree of laser excitation. In the gas laser, for example, the tube current can be adjusted to effect a change in laser beam power. This technique is unattractive since it generally provides only a limited power variation and is accompanied by change in the operating frequency of the laser.